Minimum Roof Area Before I Need Roof Drainage

Calculate the total roof area by multiplying its length by width.

Minimum roof area before i need roof drainage.

Rainfall intensities vary throughout new zealand and are often very high. Determining the exact roof area and the number of drains is precise work so it requires coordination with the building s architect. Minimum roof pitch the minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run. There are 5 easy steps to figure out how many drains your commercial roofing project will need.

Roof drainage systems need to be designed to cope with the rainfall intensities for the specific building location. An additional roof drain should be added for each 10 000 square foot area. Assume you are tasked to size a horizontal roof drain serving 5 000 square feet of roof area on a building located in dallas tx. Drainage design specific to location.

A good rule to follow is to provide two roof drains for a total roof area less than 10 000 square feet. Walls that drain onto a lower storey roof can increase the effective roof area by around 50. Determine leader or pipe size. Calculate total roof area.

It s easier to see how this works with a real world example. Roof replacement or roof recover of existing low slope roof coverings shall not be required to meet the minimum design slope requirement of one quarter unit vertical in 12 units horizontal 2 percent slope in section 1507 for roofs that provide positive roof drainage. Adding a roof can create drainage problems if the roof pitch is too shallow. Increasing the angle of a flat roof will always increase the speed of water movement across the surface.

The drainage system of any roof can be located at the edge or in the middle of the roof. A small roof with a shorter length on the other hand will not collect a lot of water within a short period of time and will work just fine with the minimum roof slope for drainage. For a large roof it is recommended to have drains placed at multiple locations within the area of the roof. Evidently there are set standards for the different kinds of roof slopes.